South African gold mining companies have signed a new wage deal aimed at ending strikes that have crippled the industry.

The deal between mineworkers' unions and three major mining companies, signed Thursday, gives mineworkers cumulative wage hikes of between 11 and 20 percent.

The increase is on top of earlier pay rises that took effect in July.

Illegal strikes by South African mine workers had intensified since August, when police opened fire on striking workers at a platinum mine and killed 34 people. Police said they were firing in self-defense.

The workers at that mine eventually won a 22-percent pay raise, a move that prompted workers at other mines to demand better pay and improved work conditions.

The strikes prompted mining companies to issue ultimatums to workers to return to work or face dismissal.

Thursday's agreement does not affect workers in the platinum and coal mining industries.